Ruy Lopez - classical defence - Zaitsev variation
1. e4 e5 2. Nf3 Nc6 3. Bb5 Bc5 4. O-O Nd4 5. b4
White moves the king's pawn to e4. Black plays the king's pawn to e5. White develops the knight to f3.
Black develops the knight to c6. White develops the light-squared bishop to b5. Black develops the dark-squared bishop to c5.
White castles kingside. Black transfers the knight to d4. White moves the b-pawn to b4.